TREATMENT OF COLON CANCER

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Once a colon cancer is diagnosed, the primary treatment is removal.  In most cases this requires surgery, but if the cancer is found at a very early stage, when it has not grown beyond the polyp where it started, it might be treated simply with complete removal of the polyp through the colonoscope.  When the polyp is removed, it is examined by a pathologist with a microscope.  If the cancer cells are only seen in the tip of the polyp but not at the base where it was cut across, then nothing else needs to be done.  Your doctor will recommend a repeat colonoscopy much sooner though, to monitor closely for any additional polyps.

If the cancer has grown into the base of the polyp or beyond, a segment of the colon needs to be removed.  Many people seem surprised at how much colon is to be removed in such cases.  The reason for removing an entire segment has to do with how colon cancer grows and spreads.  The first place that colon cancer cells might spread is into lymph nodes near the colon.  These lymph nodes are found along the blood vessels that supply the colon, and these blood vessels and lymph nodes are located in something called the mesentery of the colon.  This mesentery is a thick membrane of fatty tissue connecting the colon (and small bowel) to the back of the abdominal cavity where the blood supply originates.  In order to remove enough of the lymph nodes, one has to remove this mesentery, including the blood vessels supplying that part of the colon.  And so, the amount of colon removed is determined by which major blood vessels are removed.  Since there are about 4 major blood vessels supplying the different colon segments, the amount of colon removed basically is determined by which segment of the colon the cancer is located.

The first segment of colon is on the right side of your abdomen, and so is called the right colon (or ascending colon, which includes something called the cecum), and is supplied by the right colic artery.  The next segment of the colon crosses the upper abdomen from right to left and is called the transverse colon, supplied by the middle colic artery.  The next part of the colon descends down on the left side of the abdomen and is called the left colon (or descending colon), and is supplied by the left colic artery.  The next segment forms an S shape called the sigmoid (like the Greek letter for S, or “sigma”), and is supplied by the sigmoid artery.  Beyond the sigmoid colon is where the rectum begins.

So, if the cancer is located in the cecum or ascending colon, a right colectomy is the usual procedure.  If the cancer is in the transverse colon, the surgery will remove at least half of the transverse colon, and often the right or some of the left depending on whether the cancer is closer to the right or left side.  If the cancer is in the left, or descending colon, the left colon will be removed, and so forth.

“Open” versus “laparoscopic” colectomy

In order to remove a portion of the colon, some sort of incision must be made of course.  This traditionally has involved making a fairly long opening into the abdomen, to allow the surgeon’s hands to get down and around the colon and its blood supply.  This method has come to be referred to as the “open” or “traditional” technique, in contrast to a newer method now available.  Since the early 1990’s new techniques have been developed which allow the surgeon to use smaller incisions, using small instruments rather than his hands to do the procedure.  These various techniques are referred to as “laparoscopic” or “laparoscopic assisted” procedures.  In many cases, the necessary procedure can be achieved in this way, through a smaller incision.  Your surgeon will likely discuss these different options with you, and decide which technique seems best for you.

“Bowel prep” (cleansing of the colon) for surgery

In the past, anytime a portion of the colon was to be surgically removed, the patient had to cleanse their colon, just like what is done for colonoscopy.  This involves drinking only clear liquids for 1-3 days, and taking some laxatives or purgatives.  We now know that it doesn’t usually make any difference whether the colon is “cleaned out” or not for the surgery, the outcome seems to be the same.  And so, in most cases, the surgeons at DeKalb Surgical Associates will not make you go through the “bowel prep” prior to your surgery.  But there are situations where it still is necessary, so you can discuss this further as you prepare for your surgery.

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